Traditional film-screen radiography has been used as a medical imaging diagnostic system for well over a century. X-rays are projected through a patient's body part to form a latent radiographic image on film contained in a cassette. The film must then be chemically or thermally processed to produce a visual radiographic image which can be used by a health care professional for diagnostic purposes. The delay in obtaining a diagnostic image, the use of a chemical or thermal processor, and the difficulty in providing the radiographic film outside of the immediate medical facility, has resulted in the development of digital radiographic imaging systems. Computed radiography (CR) digital systems have been developed in recent years that provide reusable CR plates which are scanned to produce a digital radiographic image. The CR systems still result in a delay in obtaining a diagnostic image due to the necessity of scanning an exposed CR plate.
Digital radiography is achieving a growing acceptance as an alternative to film-screen and CR radiography systems. With digital radiography (DR), the radiation image exposures captured on radiation sensitive layers are converted, pixel by pixel, to digital image data which is stored and subsequently displayed on electronic display devices. This enables virtually instant access to the radiographic image and the ability to communicate a radiographic image via networks to a remote location for analysis and diagnosis by radiologists without delay in sending chemically or thermally process radiographic films by courier or through the mail. The use of chemical or thermal processors is also eliminated by digital radiography systems.
The dimensions of medical radiographic cassettes/screens/films are specified under industry standards. This includes both conventional film and CR phosphor screens, with nominal imaging areas, such as 35 cm×43 cm and 40 cm×40 cm. Standard cassette dimensions are also specified by industry standards, including a maximum cassette thickness, such as 16 mm. To be used in the same radiographic environment, it is desirable that the DR detectors meet these same industry standard dimensional requirements.
U.S. Pat. No. 5,804,832, issued Sep. 8, 1998, inventors Crowell et al., discloses a digital array for capturing a radiograph where a rigid support for the detection panel is mounted directly to a plurality of shock absorbing mounts. This requires additional parts and assembly steps to build the detector.
U.S. Pat. No. 6,700,126 B2, issued Mar. 2, 2004, inventor Watanabe, discloses a radiographic apparatus where a support for the radiation detector is rigidly fixed onto a casing. Shock absorbers are placed on the side wall(s) of the cassette.
U.S. Pat. No. 6,967,333 B2, issued Nov. 22, 2005, inventor Hata, discloses a two dimensional image pick up where shock absorber means comprise at least a first container and a second container. The containers are filed with gel, air, or other gas, to provide an “airbag” style of shock absorption between the apparatus cabinet and photoelectric converter. Shock absorption using this approach would be ineffective when the space between the apparatus and photoelectric converter is very small.
U.S. Pat. No. 5,844,961, issued Dec. 1, 1998, inventors McEvoy et al., discloses a filmless digital x-ray system that uses a standard x-ray cassette housing. An external power source provides the power for the detector and associated electronic system.
U.S. Patent Application Pub. No. 2004/0227096 A1, published Nov. 18, 2004, inventor Yagi, discloses a metal spring assembly for providing shock isolation to a radiation detector that provides limited shock isolation due to the stiffness of the metal spring type spring.
U.S. Patent Appln. Pub. No. 2005/0017188 A1, published Jan. 27, 2005, inventor Yagi, discloses means to provide shock isolation to a radiation detector, in which shock absorption material is provided between inner and outer frames. This structure increases the size of the cassette.
While such systems may have achieved certain degrees of success in their particular applications, there is a need to provide a digital radiography detector that is easy to assemble and service, while providing an auxiliary means of shock protection to internal detector components. There is also a need to prevent movement and potential damage to detector components under accidental drop-shock conditions. There is a further need to provide means of sealing the exterior of the detector from ingress of fluids so that detector components cannot be damaged.